1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device, and more particularly to a liquid crystal display device having a wire securing member that can secure a lamp wire to a mold frame and hold back free sway of the lamp wire to prevent damage to a soldering portion and shorting of the lamp wire when carrying and assembling the LCD device.
2. Description of the Related Art
Recently, information-processing devices are developing considerably to have various shapes and functions, and to process information more rapidly. Since a display device is indispensable to the information-processing device, the display device has also been improved to keep pace with rapid developments of the information-processing device.
Until the present time, CRT (Cathode Ray Tube) monitors have mainly been used as a display device for various information-processing devices. However, recently the liquid crystal display (hereinafter referred to as “LCD”) device that is light and small and requires only a little space has been developed with the features of a portable device. Such a device is being widely used as a display device for a computer, which is a typical information-processing device, a home television set that is hung on the wall and other information-processing devices.
Generally, the LCD device changes the specific molecular arrangement of the liquid crystal layer by applying a voltage to the liquid crystal layer, and it converts a variation in optical properties, such as birefringence, optical linearity, dichromatism, light scattering characteristic, etc., into a variation in visual properties. In other words, the LCD device displays information using light modulation by the liquid crystal cell.
Since the LCD device is a passive display device that does not generate a light by itself, it requires a back light assembly to supply light to the LCD device. The back light assembly includes a light source part for generating the light, and a light guide part for guiding the light generated from the light source part to an LCD panel on which an image is displayed. In a conventional LCD device, the light source part comprises one or more lamps and the light guide part is made in the form of a plate having a desired thickness.
The back light assembly, including the lamp, the light guiding plate and other supplementary members for generating and guiding light, is encased within in a container called a mold frame, thereby forming a mold frame assembly. Then, the LCD panel is secured on the mold frame assembly in a module assembly process, which completes the LCD device.
The lamp consumes 70% or more of a driving power of the LCD device; physical properties of the light guide part, such as shape, materials and the like, also have a strong relation to the size as well as the brightness of the LCD panel. Hence, the outward dimension and light efficiency of the LCD device will differ depending on the structure of the back light assembly, which influences mechanical and optical properties of the LCD device
FIG. 1 is a perspective view showing a rear surface of the conventional mold frame assembly.
Referring to FIG. 1, a mold frame assembly 90 includes a back light assembly and a mold frame 10 containing the back light assembly. The back light assembly includes a lamp unit (not shown) for generating a light and a light guide unit (not shown) for guiding the generated light to an LCD panel (not shown) on which an image is displayed.
The lamp unit includes a lamp for generating the light (not shown), a lamp reflector (not shown) that surrounds the lamp and reflects the light radiated from the lamp towards the light guide unit in order to improve the light efficiency, an inverter (not shown) for supplying a modified alternating current to the lamp, and a pair of lamp wires 22 for connecting the inverter and the lamp electrically. The lamp wire 22 is fixed or secured by soldering an end of the lamp wire 22 to the lamp. A connector 24 is installed to the other end of the lamp wire 22 to connect the lamp wire 22 to the inverter with ease and safety.
The light guide unit includes a light guide plate (hereinafter, referred as LGP) for guiding the light generated from the lamp to the LCD panel, a reflection plate installed at a lower side of the LGP so as to reflect a leakage light from the LGP to the LCD panel, and optical sheets for enhancing a light concentration property toward the LCD panel. With the aforementioned elements, the light guide unit can convert into a plane light source for the LCD panel using a linear light source generated from the lamp unit disposed at a side edge portion of the LCD panel.
Preferably, the mold frame 10 has a rectangular parallelepiped box shape and an upper portion thereof is opened. Consequently, the mold frame 10 has four sidewalls and a bottom. On the outer surface of the bottom, a support portion 12 is formed to support and secure the printed circuit board bent vertically at a latitudinal side surface of the mold frame. On a part of a longitudinal side surface perpendicular to the latitudinal side surface, a joint portion 14 is formed to joint a chassis to the mold frame. The chassis (not shown) is jointed for bending the printed circuit board along the first side surface of the mold frame and securing the printed circuit board to the support portion 12. Furthermore, a wire entry 16 is also formed next to the joint portion 14 for entering the lamp wire that connects an electrical power source (not shown) disposing out of the mold frame with the lamp disposing in the mold frame.
The mold frame assembly 90 is assembled by rendering the lamp unit disposed at an inner side of the mold frame 10 and the light guide unit positioned to an opposite side of the lamp unit in the mold frame 10.
After being assembled, the mold frame assembly 90 is transferred to a module assembly process. In the module assembly process, the LCD panel for displaying an image is mounted on the upper portion of the mold frame assembly 90 and a chassis for securing the LCD panel to the mold frame is assembled to the joint portion 14. Consequently, an LCD device is assembled completely. On this occasion, the lamp wire 22 is drawn from the wire entry 16 and connected to the inverter (not shown) for supplying an electrical power to the lamp.
When the connector 24 is connected to the inverter (not shown) to operate the LCD device, an electrical power of alternating current is supplied to the lamp through the lamp wire 22 and thus light is generated from the lamp. Subsequently, the light is guided to the LCD panel by the light guide unit and an image is displayed on the LCD panel. Hence, the lamp wire 22 of the LCD device should always be drawn and exposed out of the mold frame 10 to be supplied a current for driving the back light assembly from an external power source.
However, the exposure of the lamp wire 22 causes a connection failure and a double securing operation of the lamp wire 22 is required in manufacturing the LCD device.
Since the lamp wire 22 is always exposed out of the mold frame 10 during the transfer process of the mold frame assembly 90 or during the module assembly process, unexpected tensile forces may be applied to the lamp wire 22 when the lamp wire 22 is entangled or caught on an obstacle. Hence, the unexpected tensile force causes the soldering connection at the connector 24 to be opened and thus a connection failure may occur. Accordingly, the electrical source power cannot be applied to the lamp due to the connection failure of the lamp wire.
To prevent the lamp wire 22 from entangling or being caught on an obstacle, the mold frame assembly 90 is transferred into the module assembly process under a circumstance with the lamp wire 22 being temporarily secured to the rear surface of the mold frame assembly 90 by an adhesive such as an adhesive tape. In the module assembly process, the adhesive is removed and then the mold frame assembly 90 is assembled. After the assembly process is completed, the lamp wire is again secured to the rear surface of the mold frame using adhesive tape. After that, the LCD device is packed into the shielding bag and is shipped.
Thus, the attaching of an adhesive for securing the lamp wire is twice done repeatedly in the transfer step of the mold frame assembly 90 and the shipping step of the LCD device, which increases material cost and processing time in manufacturing an LCD device.